With the development of USB (Universal Serial Bus, Universal Serial Bus) interface standards, the transmission rate is improving. The transmission rate of the USB2.0 standard has reached 480 MB/s (Megabits per second). The upcoming USB3.0 standard will provide higher transmission rate. Currently, USB interfaces have been applied widely for transmitting data. A data card is connected to a computer through a USB interface. As shown in FIG. 1, pins 2 of a conventional USB connector 1 are welded on a bonding pad of a PCB (Printed Circuit Board) 3 directly. Four pins 2 (including two power supply pins and two data pins) on the USB connector 1 are exposed outside the PCB (Printed Circuit Board) 3. Data needs to be transmitted at a high rate on the USB connector 1, so the high-rate data transmission generates electromagnetic radiation.
The inventor finds that at least the following problems exist in the prior art. In the case that a data card (namely, a wireless modem) is also connected to the computer through a USB interface, the electromagnetic radiation generated by the USB interface generates Electro Magnetic Interference (EMI, Electro Magnetic Interference) to the data card, and deteriorates radio performance of the data card and impairs the radio performance of the whole system directly. Moreover, higher transmission rate of the USB interface leads to more EMI. Therefore, the upcoming USB3.0 standards will provide higher transmission rate and lead to grimmer EMI.